Ballistix 6400s freezing, but pass memtest?

[gurusan]

I have been getting random freezes and have finally pinned them down to a set of 6400 ballistix. They pass memtest with no errors both at stock and overclocked to 1200mhz! So wtf mang!

My set of 5300s are doing just fine in here....any idea what could be causing it? Should I just RMA the 6400s?

 

[VortexA1]

ok...well apparently even though memory passes memtest once the computer is under a sufficient load over 'the memtest' if there's not enough power to the memory it can cause errors - the 5300s maybe just a better batch.. and your 6400s not.does the 6400 need more volts??